TENDRIL CLIMBERS 



91 



In the majority of cases the direction is connter-clockwise while in a 

 smaller number it is clockwise. Among plants that twine in a coun- 

 ter-clockwise direction are the bean (Phaseolns), the bittersweet 

 (Celastms), the moonseed {Mcnispermmn), and the bittersweet night- 

 shade (Solamim dulcamara). The hop {liuniulus) and the black 

 bindweed (Polygonum scandens) twine in a clockwise direction. 



Fig. 37.— Poison ivy on hickory, climbing partly by twining and partly by 

 adventitious roots. Since the ivy grows more rapidly than the hickory it is 

 rapidly becoming too heavy for the host. 



57. Tendril Climbers.— Scarcely second to the twiners in spe- 

 cialization are the tendril climbers in which one organ or another is 

 modified into a tendril which grasps any support with which it 

 comes in contact. Tendrils are ordinarily extremely sensitive to 

 contact with solid bodies. In some cases merely stroking the tendril 

 lightly with a match-stick once or twice will cause a bending of the 



